Final answer:
The breakdown of carbohydrates begins in the mouth with the enzyme salivary amylase but is halted in the stomach due to its acidity. Fat digestion primarily occurs in the small intestine with the help of bile and lipase, while proteins begin to be digested in the stomach through the action of pepsin. The correct option is c.
Step-by-step explanation:
Chemical digestion and the breakdown of carbohydrates begin in the mouth. An enzyme called salivary amylase initiates the digestion of starches by breaking them down into maltose, a disaccharide.
This process continues as the bolus (chewed food) travels through the esophagus. However, once the bolus reaches the acidic environment in the stomach, the action of salivary amylase is halted, as the enzyme is inactivated by the stomach's acidity.
Regarding the other macronutrients, such as fats, the majority of fat digestion occurs in the small intestine facilitated by enzymes like lipase and substances such as bile, which emulsifies fats to increase the efficiency of their digestion. Proteins begin their digestion in the stomach through the action of the enzyme pepsin. The correct option is c.